/*

 * Copyright 2014 Google Inc. All rights reserved.

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#include <stddef.h>

#include <stdint.h>

#include <clocale>

#include <filesystem>

#include <string>

#include "cpp17/generated_cpp17/monster_test_generated.h"

#include "flatbuffers/idl.h"

#include "test_assert.h"

#include "test_init.h"

namespace fs = std::filesystem;

// Utility for test run.

OneTimeTestInit OneTimeTestInit::one_time_init_;

// The current executable path (see LLVMFuzzerInitialize).

static fs::path exe_path_;

static flatbuffers::Parser parser_;

namespace {

static constexpr size_t kMinInputLength = 1;

static constexpr size_t kMaxInputLength = 16384;

static constexpr uint8_t flags_strict_json = 0x80;

static constexpr uint8_t flags_skip_unexpected_fields_in_json = 0x40;

static constexpr uint8_t flags_allow_non_utf8 = 0x20;

bool TestFileExists(fs::path file_path) {

  if (file_path.has_filename() && fs::exists(file_path)) return true;

  TEST_OUTPUT_LINE("@DEBUG: file '%s' not found", file_path.string().c_str());

  for (const auto &entry : fs::directory_iterator(file_path.parent_path())) {

    TEST_OUTPUT_LINE("@DEBUG: parent path entry: '%s'",

                     entry.path().string().c_str());

  }

  return false;

}

std::string LoadBinarySchema(const char *file_name) {

  const auto file_path = exe_path_.parent_path() / file_name;

  TEST_EQ(true, TestFileExists(file_path));

  std::string schemafile;

  TEST_EQ(true,

          flatbuffers::LoadFile(file_path.string().c_str(), true, &schemafile));

  flatbuffers::Verifier verifier(

      reinterpret_cast<const uint8_t *>(schemafile.c_str()), schemafile.size());

  TEST_EQ(true, reflection::VerifySchemaBuffer(verifier));

  return schemafile;

}

std::string do_test(const flatbuffers::IDLOptions &opts,

                    const std::string input_json, const bool check_parser) {

  // (re)define parser options

  parser_.opts = opts;

  std::string jsongen;

  if (parser_.ParseJson(input_json.c_str())) {

    flatbuffers::Verifier verifier(parser_.builder_.GetBufferPointer(),

                                   parser_.builder_.GetSize());

    TEST_EQ(true, MyGame::Example::VerifyMonsterBuffer(verifier));

    TEST_NULL(

        GenText(parser_, parser_.builder_.GetBufferPointer(), &jsongen));

  } else if (check_parser) {

    TEST_OUTPUT_LINE("parser failed with JSON:\n%s", input_json.c_str());

    TEST_EQ_STR("", parser_.error_.c_str());

    TEST_ASSERT(false);

  }

  return jsongen;

};

}  // namespace

// https://google.github.io/oss-fuzz/further-reading/fuzzer-environment/

// Current working directory

// You should not make any assumptions about the current working directory of

// your fuzz target. If you need to load data files, please use argv[0] to get

// the directory where your fuzz target executable is located.

// You must not modify argv[0].

extern "C" int LLVMFuzzerInitialize(int *argc, char ***argv) {

  (void)argc;

  exe_path_ = (*argv)[0];

  static const std::string schemafile = LoadBinarySchema("monster_test.bfbs");

  // parse schema first, so we can use it to parse the data after

  parser_.Deserialize(reinterpret_cast<const uint8_t *>(schemafile.c_str()),

                      schemafile.size());

  return 0;

}

extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {

  // Reserve one byte for Parser flags and one byte for repetition counter.

  if (size < 3) return 0;

  const uint8_t flags = data[0];

  (void)data[1];  //  reserved

  data += 2;

  size -= 2;  // bypass

  const std::string original(reinterpret_cast<const char *>(data), size);

  auto input = std::string(original.c_str());  // until '\0'

  if (input.size() < kMinInputLength || input.size() > kMaxInputLength)

    return 0;

  flatbuffers::IDLOptions opts;

  opts.strict_json = (flags & flags_strict_json);

  opts.skip_unexpected_fields_in_json =

      (flags & flags_skip_unexpected_fields_in_json);

  opts.allow_non_utf8 = (flags & flags_allow_non_utf8);

  do {

    const std::string jsongen_1 = do_test(opts, input, false);

    if (!jsongen_1.empty()) {

      const std::string jsongen_2 = do_test(opts, jsongen_1, true);

      if (jsongen_1 != jsongen_2 && !opts.output_default_scalars_in_json) {

        // This gets tricky when the jsongen_1 includes a default-value, as the

        // generated jsongen_2 doesn't emit default-values. So enable default

        // scalars and re-run it.

        opts.output_default_scalars_in_json = true;

        continue;

      }

      TEST_EQ(jsongen_1, jsongen_2);

    }

  } while (0);

  return 0;

}